radiographic interpretation and CBCT images

Question 1

system of examination

8

Answer 1

symmetry
margins
bone consistency
dentition
supporting bone
any other features?
summary
proposals

Question 2

symmetry and margins here?

Answer 2

M 19
superimposition of petrous temporal bone (common in occipitomeatal view)

left cloudy sinus
* straight upper margin
* definition (cortication – white margin)

if something inside the sinus that is expanding would expect it to have a curved upper margin

straight, slightly curves at either side – suggests it is a liquid meniscus
* sign that is fluid/pus related to inflammatory sinus disease

Question 3

5 points to go through when discussing any other features of note in radiogrpah

Answer 3

Radiolucent or radiopaque

site, shape, size

margins

other structures -
* ? aetiology, and effect

provisional/differential diagnosis

Question 4

radiolucent

Answer 4

loss of previously opaque material (bone, teeth)

Question 5

radiopaque

Answer 5

increased attenuation of x-ray beam

usually unnatural substances in person – e.g. metal restorations, piercings

natural tissues tend to only show radiopaque when there has been a change to them
* increased density e.g. cortical bone Vs cancellous bone
* increased thickness e.g. overlapping teeth Vs abutting teeth
* alteration e.g. soft tissue calcification
* soft tissue within an air space

Question 6

possible sites of radiographic findings

5

Answer 6

teeht
alveolus
basal bone
other bones
extra-osseous

Question 7

possible shape of radiographic findings

4

Answer 7

circular, oval (expanding evenly)

Unilocular (simple shape, not necessarily friendly)

multilocular – scalloped margin or internal divisions, variable appearance

Irregular (concerning appearance)

Question 8

size of radiographic findings can link to

Answer 8

length of time present - not reliable

Question 9

margins of radiographic findings can be

Answer 9

well defined
* corticated (has to keep remodelling, slow growing, like a wrapper around the lesion)
* not corticated

ill-defined

Question 10

radiographic findings relation to other structures can be

Answer 10

possibly aetiological

or have an effect on them

Question 11

aetiolgical relationship possibilities for radiographc findings

Answer 11

apex of a tooth - ? vital , check clinically
* necrotic pulp, bone responds to this
* cysts, periapical periodontitis

crown of a tooth
* unerupted crown has reduced enamel epithelium around it – can undergo pathological change

Question 12

possible effects a radiographic finding can have on other structures

4

Answer 12

no effect

displacement
* indicates something growing slowly, bone needs to remodel
* but if aggressive malignant – can grow rapidly, destroying bone and moving teeth with it on its borders, usually have other features of malignant lesions

expansion
* slow growing

resorption
* more aggressive – body not able to set up response to it

Question 13

possible effects a radiographic finding can have on other structures

4

Answer 13

no effect

displacement
* indicates something growing slowly, bone needs to remodel
* but if aggressive malignant – can grow rapidly, destroying bone and moving teeth with it on its borders, usually have other features of malignant lesions

expansion
* slow growing

resorption
* more aggressive – body not able to set up response to it

Question 14

radiological sieve for provisional/differential dx

12

Answer 14

• normal
• developmental
• traumatic
• inflammatory
• cystic
• neoplastic (benign and malignant)
• osteodystrophy
• metabolic/systemic
• idiopathic unsure why it is
• iatrogenic caused by tx by HCP
• foreign body
• artefact

work throught this list from top to bottom – yes/no/maybe

Question 15

any other features on this PA

Answer 15

radiolucent
* maxilla, circular, approx. 1 cm.
* well-defined, corticated margins
* related to apices 25 and ? 26/7

provisional/differential diagnosis ?
* Extension of maxillary sinus
* Odontogenic cystic lesion (relating to non-vital tooth – old inflammatory cyst relating to tooth that was extracted)

If chance finding and asymptomatic -leave and radiograph 6months assess

Question 16

discuss

Answer 16

Deficient margins and deficient RCT

Multiple restorations in 32-42

RCT 31 & 41, extends to apex 31, but short 41 by ~ 4mm

Periapical radiolucency 41, ~ 8mm diam., well-defined but not corticated (possible sign of infection, cortication loss in infection) but here due to bone resorption

Diag. ? Radicular cyst or periapical granuloma

Question 17

discuss

Answer 17

Secondary caries or deficient margins ? and ?lesion

22 RCT, obturation variable & many materials used – inadequate

Well-defined periapical radiolucency, margins not fully shown, ~ 1cm diam.

Radiolucencies around margins restorations 21D & 22 M
* Leaking restoration with secondary caries possible

Question 18

discuss age and IDC position in this lesion of mandible

Answer 18

developing M3M, crown calcified – child

With large mandibular lesion that is well developed, cortical margin, breaches roof of IDC

Displacement of LHS IDC – shows slow going, long standing lesion

Question 19

discuss abnormality in OPT of female 16y

Answer 19

25 and 26 together at crowns, apart at roots – not what expect in 16y – possible lesion?

Can only see margin due to hard palate superimposition

CBCT – explanation
* Frontal section slice – looks like a lesion with bony margin
* Coronal view – can see antral septum, thin bone sticking into sinus – creates illusion of lesion but it is just a low sinus

Question 20

‘conventional’ CT

Answer 20

• x-ray source, thin fan shaped beam of x-rays
• corkscrew dectectors round pt
• connect to computer
• long axis of pt, thin slices
• can have axial, coronal (front to back), sagittal (side to side)
• high dose of radiation

Question 21

CBCT

Answer 21

Lower radiation dose
* X-ray beam produced is a cone shape (not thin fan beam)
* more area needed for detector
* Only round a pt once

Specifically hard tissue seen (CT is hard and soft)

3D view so can see whole area for tx planning

Question 22

clinical indications for CBCT

9

Answer 22

implant planning

impacted teeth (normal and supernumeraries)
* Location
* Relations, e.g. inferior alveolar canal
* ? related other teeth, e.g. root resorption (teeth viable still, can teeth be moved to resolve)

pathology – cystic lesions, infections, benign tumours

orthognathic surgery

hypodontia
Implant planning

cleft palate – bone defects

dental abnormalities – dilaceration, double teeth

endodontic problems

autotransplantation

Question 23

3 main general principles needed for radiographic exposure

Answer 23

justification of an individual exposure

optimisation

dose limitation

11. (1) (b) A person must not carry out an exposure unless it has been justified by the practitioner as showing a sufficient net benefit giving appropriate weight to the matters set out in paragraph (2)
    (2) The matters referred to in paragraph (1)(b) are—
    * the specific objectives of the exposure and the characteristics of the individual involved;
    * the total potential diagnostic or therapeutic benefits, including the direct health benefits to the individual and the benefits to society, of the exposure;
    * the individual detriment that the exposure may cause; and
    * the efficacy, benefits and risk of available alternative techniques having the same
    objective but involving no or less exposure to ionising radiation.

A history and clinical examination are the only acceptable means for determining that the most appropriate, and necessary, radiographic views are requested.

Question 24

EADMFR Basic Principles on the use of CBCT

Answer 24

20 basic principles, some familiar and similar to general principles, others specifically related to CBCT:

• 6. Use only when question cannot be answered adequately with lower dose method
• 8. If evaluation of soft tissues required, ? Medical CT or MRI (e.g. cancer pt)
• 9. Use smallest volume compatible with clinical situation
• 10. Choose** resolution compatible with clinical situation**

Bigger volume = bigger dose
Bigger resolution = bigger dose

Question 25

axial view

Answer 25

standing under and looking up
their right is our left

Question 26

coronal view

Answer 26

from front of pt

Question 27

sagittal view

Answer 27

from side

Question 28

slices of CBCT can make

Answer 28

panoramic style image